The use of speed bumps in school parking lots, driveways and near certain controlled crossings is well known. These bumps or warning devices for motorists are permanent structures usually formed of paving material and are not easily removed once installed. They can be very inconvenient in situations where there is only a periodic need for slow traffic, as at school crossings at the beginning and ending of the school day.
The need has been recognized for a removable device of this character as evidenced by prior U.S. Pat. No. 3,720,181, which discloses an inflatable flexible speed bump which can be placed across a roadway to warn drivers during selected periods as when school children are leaving school or entering in the morning. While the patented inflatable device is practical, it has the disadvantage of requiring installation and/or inflation at the time of each usage, and inherently, due to the inflatable and flexible nature of the device, it lacks the durability necessary for long life on a roadway having heavy traffic flow.
With the above in mind, the present invention has for its objective to provide a permanently installed retractable rigid speed bump of sturdy and durable construction which will withstand vehicular traffic indefinitely and which does not require periodic removal from the roadway site and replacement on a daily or more frequent basis. Instead, in the case of the invention, it is only necessary for a school crossing guard, or other personnel, to employ a simple manual tool and shift the speed bump from a nested non-active position wherein traffic may flow smoothly across the device to an above ground active use position where drivers will be alerted to the presence of school children at the adjacent school crossing. The invention is much more convenient than anything in the comparable prior art, is more economical over a long period of time and is much more sturdy and durable. It completely overcomes all of the principal deficiencies of the prior art.
Other features and advantages of the invention will become apparent during the course of the following description.